There being usually plenty of side clearance between the blades of a turbine, it may be deemed quite safe to lock the thrust-block in its position, by screwing the screws G up lightly, and then to turn on steam and begin running slowly.

In performing this operation it is important, during the axial movements of the spindle, to adjust the halves of the thrust-block so that there can exist no possible play which would leave the spindle free to move axially and probably vibrate badly.